f_read

The f_read function reads data from a file.

FRESULT f_read (
  FIL* FileObject,    /* Pointer to the file object structure */
  void* Buffer,       /* Pointer to the buffer to store read data */
  UINT ByteToRead,    /* Number of bytes to read */
  UINT* ByteRead      /* Pointer to the variable to return number of bytes read */
);

Parameters

FileObject
Pointer to the open file object.
Buffer
Pointer to the buffer to store read data
ByteToRead
Number of bytes to read in range of UINT.
ByteRead
Pointer to the UINT variable to return number of bytes read. The value is always valid after the function call regardless of the result.

Return Values

FR_OK (0)
The function succeeded.
FR_DENIED
The function denied due to the file has been opened in non-read mode.
FR_DISK_ERR
The function failed due to an error in the disk function.
FR_INT_ERR
The function failed due to a wrong FAT structure or an internal error.
FR_NOT_READY
The disk drive cannot work due to no medium in the drive or any other reason.
FR_INVALID_OBJECT
The file object is invalid.

Description

The file pointer of the file object increases in number of bytes read. After the function succeeded, *ByteRead should be checked to detect the end of file. In case of *ByteRead < ByteToRead, it means the R/W pointer reached end of the file during read operation.

QuickInfo

Always available.

See Also

f_open, fgets, f_write, f_close, FIL

Return